JP4566503B2 - Laser processing apparatus and semiconductor device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing apparatus for crystallizing a semiconductor substrate or a semiconductor film using a laser beam or activating after ion implantation, and a method for manufacturing a semiconductor device using the laser apparatus.
[0002]
[Prior art]
Laser annealing is performed for crystallization of a semiconductor wafer or a non-single-crystal semiconductor film in a semiconductor manufacturing process and for recovery of crystallinity after ion implantation. In the conventional laser annealing method, as disclosed in JP-A-2-181419, a method in which a laser beam is uniformly irradiated on the entire surface of an object to be irradiated, or a spot disclosed in JP-A-62-104117. The beam is processed into a linear shape by an optical system as in a method of scanning a shaped beam or a laser processing apparatus disclosed in Japanese Patent Laid-Open No. 8-195357.
[0003]
Laser annealing here refers to a technique for recrystallizing a damaged layer or an amorphous layer formed on a semiconductor substrate or semiconductor film, or a technique for crystallizing an amorphous semiconductor film formed on a substrate. . Moreover, the technique applied to planarization and surface modification of a semiconductor substrate or a semiconductor film is also included. Applicable laser oscillators are gas laser oscillators typified by excimer lasers, and solid-state laser oscillators typified by YAG lasers. The surface layer of a semiconductor is irradiated with a laser beam for several tens to several hundreds of nanoseconds. It is known to crystallize by heating for a very short time.
[0004]
For example, in Japanese Patent Laid-Open No. Sho 62-104117, the laser beam scanning speed is set to a beam spot diameter × 5000 / second or more, and the amorphous semiconductor film is polycrystallized without reaching a complete molten state. Techniques to do this are disclosed.
[0005]
The characteristics of laser annealing are that the processing time can be greatly shortened compared to annealing methods using radiation heating or conduction heating, and the substrate or semiconductor film is selectively and locally heated to cause almost thermal damage to the substrate. Is not given.
[0006]
In recent years, laser annealing has been actively used to form a polycrystalline silicon film on a glass substrate, and this process is applied to manufacture a thin film transistor (TFT) used as a switching element of a liquid crystal display device. When an excimer laser is used, only the region where the semiconductor film is formed has a thermal influence, so that an inexpensive glass substrate can be used, and application to a large area display is realized.
[0007]
In addition, since a TFT made of a polycrystalline silicon film crystallized by laser annealing can be driven at a relatively high frequency, not only a switching element provided in a pixel but also a driving circuit can be formed on a glass substrate. ing. The pattern design rule is about 5 to 20 μm, and 10 for each of the drive circuit and the pixel portion. ⁶ -10 ⁷ About a few TFTs are built on a glass substrate.
[0008]
[Problems to be solved by the invention]
Crystallization of amorphous silicon by laser annealing is performed through a process of melting and solidification, and in detail, it is considered that it is divided into stages of generation of crystal nuclei and crystal growth from the nuclei. However, laser annealing using a pulsed laser beam cannot control the generation position and generation density of crystal nuclei, and is left to occur naturally. Accordingly, the crystal grains are formed at an arbitrary position within the surface of the glass substrate, and only a small size of about 0.2 to 0.5 μm is obtained. A large number of defects are generated at the crystal grain boundary, which is considered to be a factor that limits the field effect mobility of the TFT.
[0009]
However, in the technique disclosed in Japanese Patent Laid-Open No. 62-104117, since the semiconductor film is not completely melted, crystal growth caused by crystal nuclei, which is said to be formed in the non-melted region, is dominant, and the crystal is large. Particle size cannot be realized. Specifically, a substantially single crystal crystal cannot be formed over the entire surface of the semiconductor film forming the channel region of the TFT.
[0010]
In the first place, it is considered that a method of crystallizing while scanning and melting and solidifying a continuous wave laser is a method close to the zone melting method. In order to melt the semiconductor, a high energy density is required, but it is difficult to achieve high output with a continuous wave laser, and there is a disadvantage that the apparatus becomes large. Eventually, the optical system will focus the beam small and irradiate the semiconductor. However, it takes a considerable amount of processing time to achieve crystallization over the entire surface of the large-area substrate.
[0011]
A laser beam capable of heating a semiconductor film exists in a wide range from the ultraviolet region to the infrared region. However, in order to selectively heat a semiconductor film or a semiconductor region formed in a substrate shape, absorption of the semiconductor is required. It is preferable to apply a laser beam having a wavelength in the ultraviolet range to the visible light range in relation to the coefficient. However, the laser beam emitted from the solid-state laser oscillation device has strong coherence and interference occurs on the irradiation surface, and thus a uniform laser beam cannot be irradiated.
[0012]
The present invention has been made in view of the above-described problems. A crystal semiconductor film having a large grain size with high throughput is obtained by irradiating the entire surface of a large area substrate with a laser beam in accordance with the position where the TFT is formed. An object is to provide a laser processing apparatus that can be formed.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, the present invention provides a first movable mirror that deflects a laser beam in the main scanning direction, and a long length that receives the laser beam deflected in the main scanning direction and scans it in the sub-scanning direction. The second movable mirror, and the second movable mirror scans the laser beam in the sub-scanning direction at a rotation angle about the longitudinal axis, and applies the laser beam to the workpiece on the mounting table. It is a laser processing apparatus provided with the means to irradiate.
[0014]
In another aspect of the invention, the first movable mirror that deflects the laser beam in the first main scanning direction and the laser beam deflected in the first main scanning direction are received and scanned in the first sub-scanning direction. A first laser beam scanning system having a long second movable mirror, a third movable mirror for deflecting the laser beam in the second main scanning direction, and a laser beam deflected in the second main scanning direction are received. Then, the second laser beam scanning system having a long fourth movable mirror that scans in the second sub-scanning direction, and the second movable mirror has a rotation angle centered on the axis in the long direction, Means for scanning the laser beam in the first sub-scanning direction and irradiating the workpiece on the mounting table with the laser beam and the fourth movable mirror have a laser beam having a rotation angle around the longitudinal axis. Is scanned in the second sub-scanning direction A laser processing apparatus and a means for irradiating the laser beam on the object to be processed on the mounting table.
[0015]
As a suitable form, a galvanometer mirror or a polygon mirror can be applied to the first and third movable mirrors.
[0016]
In addition, a solid-state laser or a gas laser is applied to a laser oscillation device that supplies a laser beam.
[0017]
In the configuration of the above invention, the laser beam is scanned in the main scanning direction by the first movable mirror and is scanned in the sub-scanning direction by the second movable mirror, thereby irradiating the laser beam to an arbitrary position on the workpiece. Is possible. Further, by providing a plurality of such laser beam scanning means and irradiating the surface to be formed with the laser beam from the biaxial direction, the time for laser processing can be shortened.
[0018]
The laser processing apparatus of the present invention includes a plurality of optical systems including a laser oscillation apparatus and a first deflection unit that deflects a laser beam output from the laser oscillation apparatus in the main scanning direction. And a second deflection unit that receives a plurality of laser beams deflected in the main scanning direction and scans in the sub-scanning direction. Here, the second deflecting means has a function of scanning a plurality of laser beams in the sub-scanning direction with a rotation angle about the axis in one axis direction and irradiating the workpiece on the mounting table with the laser beams. Have.
[0019]
As the first deflecting means, a movable mirror capable of arbitrarily setting the rotation angle is suitable, and a galvanometer mirror can be typically applied. As the second deflecting means, a movable mirror having an area capable of receiving a plurality of laser beams and having a long area and being rotatable about an axis in the longitudinal direction is suitable. Depending on the rotation angle of these two mirrors, the laser beam applied to the object to be processed can be applied to any position in the main scanning direction and the sub-scanning direction. Further, the laser beam can be scanned by continuously changing the angles of the two mirrors.
[0020]
As another configuration, an optical system including a laser oscillation device and a first deflecting unit that deflects the laser beam output from the laser oscillation device in the first main scanning direction is set as one set, and this is arranged in one direction. A plurality of laser diodes arranged and receiving a laser beam deflected in the first main scanning direction and scanning in the first sub-scanning direction, a laser oscillation device, and a laser beam output from the laser oscillation device A plurality of optical systems including a third deflecting means for deflecting the light beam in the second main scanning direction, a plurality of optical systems arranged in one direction, receiving a laser beam deflected in the second main scanning direction, And a fourth deflection unit that scans in the second sub-scanning direction. Here, the second and fourth deflecting means scan a plurality of laser beams in the sub-scanning direction at a rotation angle about the axis in one axis direction, and irradiate the workpiece on the mounting table with the laser beams. It has a function to do. With this configuration, it is possible to increase the number of laser beams that can irradiate and scan an object to be processed, and shorten the time required for laser processing.
[0021]
In the configuration of the optical system, an fθ lens is provided as means for correcting the scanning speed to be constant regardless of the irradiation angle. As the laser oscillation device, a gas laser oscillation device and a solid-state laser oscillation device are applied, and in particular, a laser oscillation device capable of continuous oscillation is applied. As continuous wave solid state laser oscillators, YAG, YVO _Four , YLF, YAl _Five O ₁₂ A laser oscillation apparatus using a crystal in which Nd, Tm, or Ho is doped in a crystal such as is applied. The fundamental wave of the oscillation wavelength varies depending on the material to be doped, but oscillates at a wavelength of 1 μm to 2 μm. In order to crystallize the amorphous semiconductor film, in order to selectively absorb the laser beam by the semiconductor film, a laser beam having a wavelength from the visible region to the ultraviolet region is applied, and the second harmonic to the fourth harmonic of the fundamental wave are applied. Preferably harmonics are applied. Typically, during crystallization of amorphous silicon, Nd: YVO _Four A second harmonic (532 nm) of a laser (fundamental wave 1064 nm) is used. In addition, a gas laser oscillation device such as an argon laser, a krypton laser, or an excimer laser can be used.
[0022]
The laser beam emitted and emitted from the solid-state laser oscillation device is highly coherent and causes interference on the irradiation surface. As a means to cancel this, the multiple laser beams emitted from different laser oscillation devices are irradiated. In FIG. By adopting such a configuration, it is possible not only to remove interference, but also to increase the substantial energy density in the irradiation unit. As another means, a plurality of laser beams emitted from different laser oscillation devices may be superposed on the same optical axis in the middle of the optical system.
[0023]
The configuration of the laser processing apparatus provided with the means for removing the interference has n (n = natural number) optical systems, and the nth optical system includes an nth laser oscillation apparatus and an nth Yth optical system. A deflecting means for manipulating the laser beam in the axial direction, a deflecting means for scanning the laser beam in the n-th X-axis direction, and an n-th fθ lens are condensed and deflected by n optical systems. The n laser beams can be realized with a configuration that irradiates substantially the same position of the workpiece. A galvanometer mirror can be applied as the deflecting means.
[0024]
With the configuration of the laser processing apparatus, a laser beam having an energy density sufficient to melt the semiconductor film can be irradiated without causing interference in the irradiation unit. Further, the amorphous semiconductor film can be crystallized over the entire surface of the large area substrate by scanning the laser beam with the deflecting means.
[0025]
In addition, the laser beam need not be irradiated by scanning the entire surface of the object to be processed, and it is only necessary to specify a location and irradiate only a specific area. However, the laser processing apparatus of the present invention is configured by combining a plurality of movable mirrors. It has realized it. Furthermore, the influence of interference can be removed by superimposing the laser beam on the same irradiation part.
[0026]
On the other hand, a method for manufacturing a semiconductor device according to the present invention for solving the above-described problems includes a first deflection unit that deflects a plurality of laser beams in the main scanning direction and a second deflection unit that scans in the sub-scanning direction. By scanning the plurality of laser beams in one direction, the semiconductor film having an amorphous structure formed on the insulating surface is crystallized or the crystallinity of the semiconductor film is recovered. The scanning direction of the laser beam is aligned with the channel length direction of the TFT, whereby the generation probability of a crystal grain boundary intersecting with the channel length direction can be reduced and the carrier mobility can be improved.
[0027]
As another configuration, a first deflecting unit that deflects a plurality of first laser beams in the first main scanning direction, a second deflecting unit that scans in the first sub-scanning direction, and a plurality of second laser beams that are in the second main scanning direction. An amorphous semiconductor formed on an insulating surface by scanning the plurality of laser beams in one direction by a third deflecting means for deflecting in the scanning direction and a fourth deflecting means for scanning in the second sub-scanning direction. The film is crystallized or crystallinity is restored.
[0028]
The laser beam is a laser beam output from a continuous wave solid-state laser oscillator, and has an absorption coefficient of 10 in order to selectively overheat the semiconductor film. ^Three cm ^-1 It is desirable that the laser beam has a wavelength band as described above. For a semiconductor such as silicon or silicon germanium, a laser beam in a wavelength band (visible region to ultraviolet region) having a wavelength of 700 nm or less is desirable.
[0029]
The region to be irradiated with the laser beam does not need to be the entire surface of the semiconductor film. If the selected region of the amorphous semiconductor film is crystallized or crystallinity is recovered by intermittently irradiating the laser beam. good.
[0030]
With the above structure, a crystalline semiconductor film with a large grain size can be obtained with high throughput by irradiating a laser beam and crystallizing the entire area of the large-area substrate approximately at the position where the TFT is formed.
[0031]
Note that the amorphous semiconductor film referred to in the present invention is not limited to a film having a completely amorphous structure, but includes a state in which fine crystal particles are included, or a so-called microcrystalline semiconductor film, local In particular, a semiconductor film including a crystal structure is included. Typically, an amorphous silicon film is applied, and in addition, an amorphous silicon germanium film, an amorphous silicon carbide film, or the like can also be applied.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0033]
[Embodiment 1]
FIG. 23 shows an example of the laser processing apparatus of the present invention. The illustrated laser processing apparatus includes a solid state laser 11 capable of continuous oscillation or pulse oscillation, a lens 12 such as a collimator lens or a cylindrical lens for condensing the laser beam, a fixed mirror 13 that changes the optical path of the laser beam, and a laser beam. A galvanometer mirror 14 that scans radially in a two-dimensional direction and a movable mirror 15 that receives the laser beam from the galvanometer mirror 14 and directs the laser beam to the irradiated surface of the mounting table 16 are provided. By crossing the optical axis of the galvano mirror 14 and the optical axis of the movable mirror 15 and rotating the mirror in the θ direction shown in the drawing, the laser beam can be scanned over the entire surface of the substrate 17 placed on the mounting table 16. it can.
The movable mirror 15 can be an fθ mirror to correct the beam path on the irradiated surface by correcting the optical path difference.
[0034]
FIG. 23 shows a system in which a laser beam is scanned in the uniaxial direction of the substrate 17 placed on the mounting table 16 by the galvanometer mirror 14 and the movable mirror 15. As shown in FIG. 24, as a more preferable form, in addition to the configuration of FIG. 23, a half mirror 18, a fixed mirror 19, a galvano mirror 20, and a possible mirror 21 are added, and a laser beam is simultaneously emitted in two directions (X and Y directions). May be scanned. With such a configuration, the processing time can be shortened. The galvanometer mirrors 14 and 20 may be replaced with polygon mirrors.
[0035]
Preferred lasers are solid state lasers, YAG, YVO _Four , YLF, YAl _Five O ₁₂ A laser using a crystal doped with Nd, Tm, or Ho is applied. The fundamental wave of the oscillation wavelength varies depending on the material to be doped, but oscillates at a wavelength of 1 μm to 2 μm. For crystallizing the non-single-crystal semiconductor film, it is preferable to apply the second to fourth harmonics of the oscillation wavelength in order to selectively absorb the laser beam with the semiconductor film. Typically, when crystallizing amorphous silicon, a second harmonic (532 nm) of an Nd: YAG laser (fundamental wave 1064 nm) is used.
[0036]
The oscillation may be either pulse oscillation or continuous oscillation, but it is desirable to select the continuous oscillation mode in order to continuously grow the crystal while maintaining the molten state of the semiconductor film.
[0037]
When a TFT is formed using a semiconductor film crystallized by laser annealing on a substrate, high field-effect mobility can be obtained by aligning the crystal growth direction and the carrier movement direction. That is, the field effect mobility can be substantially increased by matching the crystal growth direction with the channel length direction.
[0038]
In the case where the non-single crystal semiconductor film is irradiated with a continuous oscillation laser beam to be crystallized, the solid-liquid interface is maintained, and continuous crystal growth can be performed in the scanning direction of the laser beam. As shown in FIG. 24, in a TFT substrate (mainly a substrate on which TFTs are formed) 22 for forming an active matrix type liquid crystal display device integrated with a drive circuit, drive circuit portions 24 and 25 around a pixel portion 23. Is provided. FIG. 24 shows a form of a laser processing apparatus in consideration of such a layout. By adopting a configuration in which a laser beam is incident from two axial directions, a combination of galvanometer mirrors 14 and 20 and movable mirrors 15 and 21 is used. It is possible to irradiate the laser beam synchronously or asynchronously in the X and Y directions indicated by arrows in FIG. That is, it is possible to irradiate a laser beam by designating a location in accordance with the TFT layout.
[0039]
Next, with reference to FIGS. 25A and 25B, crystallization of a non-single crystal semiconductor film and a process of forming a TFT using the formed crystal semiconductor film will be described. FIG. 25 (1 -B) is a longitudinal sectional view, and a non-single crystal semiconductor film 53 is formed on a glass substrate 51. A typical example of the non-single-crystal semiconductor film 53 is an amorphous silicon film. In addition, an amorphous silicon germanium film or the like can be used. Although a thickness of 10 to 200 nm can be applied, the thickness may be further increased depending on the wavelength and energy density of the laser beam. In addition, it is desirable to provide a blocking layer 52 between the glass substrate 51 and the non-single-crystal semiconductor film 53 so as to prevent impurities such as alkali metals from diffusing from the glass substrate into the semiconductor film. As the blocking layer 52, a silicon nitride film, a silicon oxynitride film, or the like is applied.
[0040]
Crystallization is performed by irradiation with the laser beam 50, and a crystalline semiconductor film 54 can be formed. As shown in FIG. 25 (1-A), the laser beam 50 is scanned in accordance with the position of the assumed semiconductor region 55 of the TFT. The beam shape can be arbitrary, such as rectangular, linear, elliptical. The energy intensity of the laser beam condensed by the optical system is not necessarily constant at the center and at the end, so that it is desirable that the semiconductor region 55 does not reach the end of the beam.
[0041]
The laser beam may be scanned not only in one direction but also in reciprocal scanning. In that case, it is possible to change the laser energy density for each scanning and to grow crystals in stages. It is also possible to serve as a hydrogen removal process that is often required when crystallizing amorphous silicon. First, scan at a low energy density, release hydrogen, increase the energy density, and scan a second time. The crystallization may be completed with.
[0042]
Thereafter, as shown in FIGS. 25 (2-A) and (2-B), the formed crystalline semiconductor film is etched to form semiconductor regions 55 divided into island shapes. In the case of the top gate type TFT, the gate insulating film 56, the gate electrode 57, and the one conductivity type impurity region 58 can be formed on the semiconductor region 55 to form the TFT. Thereafter, a wiring, an interlayer insulating film, or the like may be formed as necessary.
[0043]
In such a laser beam irradiation method, a crystal having a large grain size can be grown by irradiating a continuous wave laser beam. Of course, it is necessary to appropriately set detailed parameters such as the scanning speed and energy density of the laser beam, but this can be realized by setting the scanning speed to 10 to 80 cm / sec. The crystal growth rate after melting and solidification using a pulsed laser is said to be 1 m / sec, but the continuous crystal at the solid-liquid interface is scanned by scanning the laser beam at a slower rate and cooling it slowly. Growth is possible, and a large crystal grain size can be realized.
[0044]
In such a situation, the laser processing apparatus of the present invention is capable of crystallizing by irradiating a laser beam by designating an arbitrary position of the substrate, and irradiating the laser beam from two axial directions. Thus, the throughput can be further improved.
[0045]
[Embodiment 2]
FIG. 1 shows a laser processing apparatus according to the present invention, which shows an example of a configuration using a plurality of laser oscillation apparatuses. The laser processing apparatus shown in FIG. 1 is a laser processing apparatus capable of simultaneously irradiating a workpiece with a plurality of laser beams and scanning the laser beams.
[0046]
The illustrated laser processing apparatus includes a solid-state laser oscillation apparatus 101 capable of continuous oscillation or pulse oscillation, a lens 102 such as a collimator lens or a cylindrical lens for condensing a laser beam, a fixed mirror 103 that changes an optical path of the laser beam, a laser A first movable mirror 104 that scans the beam radially in a two-dimensional direction and an fθ lens 105 that makes the scanning speed constant when the laser beam is scanned are provided. Here, for convenience, these configurations are collectively regarded as one optical system. The laser processing apparatus shown in FIG. 1 shows a configuration in which five such optical systems are arranged. Of course, the number of optical systems is not limited, and it is sufficient if a means for supplying a plurality of laser beams is provided.
[0047]
Furthermore, a second movable mirror 106 is provided that receives a plurality of laser beams supplied from a plurality of optical systems and deflects the laser beam to the workpiece 108 of the mounting table 107. In order to scan the laser beam in the main scanning direction and the sub-scanning direction, the optical axes of the first movable mirror 104 and the second movable mirror 106 are crossed. With such a configuration, the laser beam can be scanned over the entire surface of the workpiece 108 placed on the mounting table 107. The first movable mirror 104 and the second movable mirror 106 in this configuration are used as deflection means.
[0048]
The laser beam irradiated to the object to be processed is reflected on the surface and incident on the optical system again to cause damage to the laser oscillation device. Therefore, the laser beam is incident on the object to be processed at a predetermined angle. It is desirable to make it.
[0049]
Here, the configuration in which the fθ lens 105 is provided in the optical system is shown, but instead, the second movable mirror 106 may be an fθ mirror, and the beam shape on the irradiated surface may be corrected by correcting the optical path difference. .
[0050]
A preferable laser oscillation device is a solid-state laser oscillation device, such as YAG, YVO. _Four , YLF, YAl _Five O ₁₂ A laser oscillation apparatus using a crystal in which Nd, Tm, or Ho is doped in a crystal such as is applied. The fundamental wave of the oscillation wavelength varies depending on the material to be doped, but oscillates at a wavelength of 1 μm to 2 μm. For crystallizing the non-single-crystal semiconductor film, it is preferable to apply the second to fourth harmonics of the oscillation wavelength so that the semiconductor film can selectively absorb the laser beam. Typically, the second harmonic (532 nm) of an Nd: YAG laser (fundamental wave 1064 nm) is used for crystallization of amorphous silicon. In addition, a gas laser oscillation device such as an argon laser, a krypton laser, or an excimer laser can be used. The oscillation may be either pulse oscillation or continuous oscillation, but it is desirable to select the continuous oscillation mode in order to continuously grow the crystal while maintaining the molten state of the semiconductor film.
[0051]
The fundamental wave can be modulated into a second harmonic, a third harmonic, and a fourth harmonic by a wavelength converter including a nonlinear element. This wavelength converter may be incorporated into a part of the optical system described above or incorporated in the laser oscillation apparatus body. In the laser oscillation device 101 shown in FIG. 1, it is assumed that a wavelength converter is incorporated in the laser oscillation device body.
[0052]
The configuration of the laser processing apparatus shown in FIG. 2 is the same as in FIG. 1, the laser oscillation apparatus 101 capable of continuous oscillation or pulse oscillation, the lens 102 such as a collimator lens or a cylindrical lens for condensing the laser beam, the laser beam A plurality of optical systems including a fixed mirror 103 that changes the optical path of the laser beam and a first movable mirror 104 that radially scans a laser beam in a two-dimensional direction are arranged, and a plurality of long second movable mirrors 106 are correspondingly provided. The provided structure is shown. In such a configuration as well, the laser beam can be scanned over the entire surface of the workpiece 108 placed on the mounting table 107. Moreover, it is good also as a structure provided with the f (theta) lens or the f (theta) mirror.
[0053]
The configuration of the laser processing apparatus shown in FIG. 3 is to combine a plurality of laser beams into a single laser beam using a fixed mirror 110 and a prism 111 using a plurality of laser oscillation apparatuses 101 for a set of optical systems. In this configuration, the light enters the fixed mirror 103. By synthesizing laser beams with different phases radiated from different laser oscillation devices, it is possible to suppress distribution of energy density due to interference in the irradiation unit. Other configurations are the same as in FIG. 1, and the lens 102, the fixed mirror 103, the first movable mirror 104, the fθ lens 105, and the second movable mirror 106 are provided, and the workpiece 108 is placed on the mounting table 107. It has become.
[0054]
FIG. 4 shows a configuration in which a plurality of laser beams supplied from a plurality of optical systems are irradiated from two different directions as another embodiment of the laser processing apparatus. In the configuration of FIG. 4, a first optical system including a laser oscillation device 101, a lens 102, a fixed mirror 103, and a first movable mirror 104, and a laser oscillation device 101, a lens 102, a fixed mirror 150, and a first movable mirror 151 are included. A second optical system, a first path for irradiating the workpiece 108 on the mounting table 107 by the second movable mirror 106 with a plurality of laser beams, and a second path on the mounting table 107 by the second movable mirror 152. A second path for irradiating the workpiece 108 with a plurality of laser beams is provided, and by simultaneously operating both, it is possible to further reduce the processing time.
[0055]
When a TFT is formed of a crystalline semiconductor film crystallized by laser annealing on a substrate, high field-effect mobility can be obtained by aligning the crystal growth direction and the carrier movement direction. That is, the field effect mobility can be substantially increased by matching the crystal growth direction with the channel length direction. When crystallization is performed by irradiating a non-single-crystal semiconductor film with a continuously oscillating laser beam, the solid-liquid interface is maintained, and continuous crystal growth can be performed in the scanning direction of the laser beam.
[0056]
An active matrix display device using TFT can be divided into a pixel part and a driver circuit part from the functional division. In TFTs using a crystalline semiconductor film, they can be integrally formed on the same substrate. Here, the substrate in which these are integrally formed is called a TFT substrate, but in the production process, a method is implemented in which a plurality of TFT substrates are made on a large glass substrate (called mother glass) and divided at the final stage of the process. Has been.
[0057]
FIG. 5 shows details of a region 200 surrounded by a two-dot chain line in FIG. As shown in FIG. 5, in a TFT substrate 201 for forming an active matrix display device integrated with a drive circuit on an object to be processed 108 (mother glass), drive circuit portions 203 and 204 are provided around a pixel portion 202. It has been. As described with reference to FIG. 4, in the configuration in which the laser beam is irradiated from two directions, the combination of the first movable mirror 104 and the second movable mirror 106 and the first movable mirror 151 and the second movable mirror 152 in the drawing. The laser beam can be irradiated synchronously or asynchronously in the X direction and the Y direction as shown in FIG. 5B, and the laser beam can be irradiated by designating a location in accordance with the TFT layout.
[0058]
With the configuration of the laser processing apparatus, a laser beam having an energy density sufficient to melt the semiconductor can be irradiated without causing interference in the irradiation unit. Further, the amorphous semiconductor film can be crystallized over the entire surface of the large area substrate by scanning the laser beam with the deflecting means. In addition, it is not necessary to scan and irradiate the entire surface of the object to be processed, and it is only necessary to specify a location and irradiate only a specific area. However, the laser processing apparatus is configured by combining a plurality of movable mirrors. Realized. Furthermore, the influence of interference can be removed by superimposing the laser beam on the same irradiation part.
[0059]
[Embodiment 3]
A structure capable of superimposing laser beams on the irradiation surface, obtaining an energy density necessary for laser processing, and removing light interference will be described with reference to FIGS. FIG. 9 is a top view showing the configuration of such a laser processing apparatus, and FIG. 10 is a cross-sectional view corresponding thereto, illustrating the same configuration from different angles.
In FIG. 9 and FIG. 10, the common code | symbol is used for convenience of explanation.
[0060]
The first optical system 401 includes a laser oscillation device 301a, a lens group 302a, a first galvanometer mirror 303a, a second galvanometer mirror 304a, and an fθ lens 305a. Here, the first galvanometer mirror 303a and the second galvanometer mirror 304a are provided as deflection means.
[0061]
The second optical system 402 and the third optical system 403 have the same configuration, and the direction of deflection of the laser beam is controlled by the rotation angle of the first galvanometer mirror and the second galvanometer mirror, and the object 307 on the mounting table 306 is applied. Irradiated. The beam can be formed into an arbitrary shape by providing a lens group 302 and, if necessary, a slit or the like, but may be a circle, an ellipse, or a rectangle of approximately several tens to several hundreds of μm. Although the mounting table 306 is fixed, it can be synchronized with the scanning of the laser beam, and thus may be movable in the XYθ direction.
[0062]
Then, by superimposing the laser beams irradiated on the object to be processed by the first to third optical systems, it is possible to obtain an energy density necessary for the laser processing and to remove light interference. Since laser beams emitted from different laser oscillation devices have different phases, interference can be reduced by superimposing them.
[0063]
Here, a configuration in which three laser beams emitted from the first to third optical systems are superimposed is shown, but the same effect is not limited to this number, and a plurality of laser beams are superimposed. The purpose is achieved.
[0064]
[Embodiment 4]
The laser processing apparatus of the present invention can be applied to crystallization of an amorphous semiconductor film, recovery of crystallinity of an ion implantation region, and activation of a valence electron control impurity. FIG. 11 is a diagram for explaining a laser processing step in crystallization of an amorphous semiconductor film.
[0065]
In FIG. 11A, a blocking layer 1002 and an amorphous semiconductor film 1003 are formed over a substrate 1001. The laser beam irradiation unit 1005 may be irradiated in accordance with a position including the semiconductor region 1004 for forming the TFT. The irradiation unit 1005 scans a region wider than the semiconductor region 1004 and crystallizes the region including the peripheral portion of the semiconductor region 1004. However, it is not necessary to crystallize the entire surface of the amorphous semiconductor film 1003.
[0066]
Crystallization of the amorphous semiconductor film causes release of hydrogen contained and densification due to rearrangement of atoms, resulting in volume shrinkage. Accordingly, lattice continuity is not ensured at the interface between the amorphous region and the crystal region, and distortion occurs. Inclusion of the TFT semiconductor region 1004 inside the crystallization region 1006 as shown in FIG. 11A also means removing this strain region.
[0067]
After the laser treatment, as shown in FIG. 11B, an unnecessary portion of the amorphous semiconductor film 1003 and the crystallized region 1006 is removed by etching, so that a semiconductor region 1004 is formed. After that, as shown in FIG. 11C, a gate insulating film 1007 and a gate electrode 1008 are formed, source and drain regions are formed in a semiconductor region, and a necessary wiring is provided, so that a TFT can be formed. .
[0068]
An active matrix display device using TFT can be divided into a pixel portion and a drive circuit portion in terms of functional classification. In TFTs using a crystalline semiconductor film, they can be integrally formed on the same substrate. FIG. 12 shows the relationship between the TFT substrate 1201 and the laser beam irradiation direction in detail. A region where the pixel portion 1202 and the drive circuit portions 1203 and 1204 are formed on the TFT substrate 1201 is indicated by a dotted line. In the crystallization stage, a non-single-crystal semiconductor film is formed on the entire surface, but a semiconductor region for forming a TFT can be specified by an alignment marker or the like formed on the edge of the substrate.
[0069]
For example, the driver circuit portion 1203 is a region where a scanning line driver circuit is formed, and a partially enlarged view 1301 shows the scanning directions of the TFT semiconductor regions 1251 and 1252 and the laser beams 1401a and 1401b. The semiconductor regions 1251 and 1252 can have any shape, but in any case, the channel length direction and the laser beam scanning direction are aligned. That is, the scanning direction of the laser beam 1401a with respect to the semiconductor region 1251 and the scanning direction of the laser beam 1401b with respect to the semiconductor region 1252 are different even in the same drive circuit portion.
[0070]
A driver circuit portion 1204 disposed in a direction intersecting with the driver circuit portion 1203 is a region where a data line driver circuit is formed. (Enlarged view 1302). Similarly, the pixel portion 1202 scans the array of semiconductor regions 1255 and 1256 with laser beams 1403a and 1403b in the channel length direction as shown in an enlarged view 1303. The arrangement of the semiconductor regions 1255 and 1256 shown in the enlarged view 1303 can be a delta arrangement.
[0071]
On the other hand, as shown in FIG. 13, the arrangement of the semiconductor regions formed on the TFT substrate 1201 can be arranged in the same direction in all of the pixel portion 1202 and the driver circuit portions 1203 and 1204. The scanning direction of the semiconductor region 1258 and the laser beam 1405 in the enlarged view 1305 in FIG. 13, the scanning direction of the semiconductor region 1257 and the laser beam 1404 in the enlarged view 1304, and the scanning direction of the semiconductor region 1259 and the laser beam 1406 in the enlarged view 1306 are all the same. The direction. With this arrangement, all the laser beams need only be scanned in the same direction, so that the processing time can be further shortened.
[0072]
In such a laser beam irradiation method, a crystal having a large grain size can be grown by irradiating a continuous wave laser beam. Of course, it is necessary to appropriately set detailed parameters such as the scanning speed and energy density of the laser beam, but this can be realized by setting the scanning speed to 10 to 80 cm / sec. The crystal growth rate after melting and solidification using a pulsed laser is said to be 1 m / sec, but the continuous crystal at the solid-liquid interface is scanned by scanning the laser beam at a slower rate and cooling it slowly. Growth is possible, and a large crystal grain size can be realized.
[0073]
The scanning direction of the laser beam is not limited to one direction, and reciprocal scanning may be performed. Such laser beam scanning can be performed by the laser processing apparatus having the structure shown in Embodiment Modes 1 and 2. The laser processing apparatus of the present invention enables crystallization by irradiating a laser beam by designating an arbitrary position of the substrate, and further irradiating a plurality of laser beams from two axial directions, thereby further increasing the throughput. Can be improved.
[0074]
【Example】
[Example 1]
A detailed configuration of the laser processing apparatus of the present invention based on the configuration of FIG. 4 will be described with reference to FIGS. 6 is a top view of the laser processing apparatus of the present invention, and FIG. 7 is a cross-sectional view corresponding thereto. Further, FIG. 8 is a diagram for explaining a connection path of control signals. Since these figures are related to each other, the same reference numerals are used for convenience.
[0075]
In FIG. 6, a plurality of laser beams are irradiated from two directions of the X direction and the Y direction. From the X direction, the laser beam emitted from the laser oscillation devices 501a to 501e is irradiated to the object to be processed by the lens group 502, the fixed mirror 503, the first movable mirror 504, the fθ lens 505, and the second movable mirror 506. . The laser beam is deflected by the first movable mirror 504 and the second movable mirror 506 and can scan the irradiation surface of the object to be processed. Further, from the Y direction, the laser beam emitted from the laser oscillation devices 501f to 501j is irradiated to the object to be processed by the lens group 502, the fixed mirror 507, the first movable mirror 508, the fθ lens 509, and the second movable mirror 510. Is done.
[0076]
As shown in side view A and side view B in FIG. 7, the path of the laser beam incident from the X direction and the path of the laser beam incident from the Y direction are arranged with a step so that the apparatus can be miniaturized. it can. The mounting table for holding the object to be processed is disposed below the laser beam. In any case, the laser beam incident on the object to be processed is incident at a specific angle. The laser beam incident on the object to be processed can be irradiated to a specific irradiation position by a pair of movable mirrors. The radiation of the laser beam and the angles of the first movable mirrors 504 and 508 and the second movable mirrors 506 and 510 and The loading / unloading of the object to be processed by the conveying means 511 from the cassette 512 holding the object to be processed is centrally controlled by the control means 520 as shown in FIG.
[0077]
Laser beam irradiation is performed in an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere depending on the purpose. The object to be processed is provided with gas supply means 513 as means for controlling the atmosphere of the processing chamber in which it is disposed. In addition, gas circulation means 514 for circulating the gas inside the processing chamber is provided. Although not shown here, a means for controlling the processing chamber to be depressurized may be provided.
[0078]
By scanning the laser beam with the structure of the laser processing apparatus, the amorphous semiconductor film can be crystallized over the entire surface of the large-area substrate. In addition, the laser beam can be irradiated only in a specific area by specifying a place, rather than scanning and irradiating the entire surface of the object to be processed. The configuration of the laser processing apparatus can be achieved by combining a plurality of movable mirrors. It has been realized. Furthermore, the influence of interference can be removed by superimposing the laser beam on the same irradiation part.
[0079]
[Example 2]
With reference to FIGS. 14A and 14B, crystallization of an amorphous semiconductor film and a process of forming a TFT using the formed crystalline semiconductor film will be described. FIG. 14 (1 -B) is a vertical cross-sectional view, and a non-single-crystal semiconductor film 603 is formed over a glass substrate 601. A typical example of the non-single-crystal semiconductor film 603 is an amorphous silicon film; in addition, an amorphous silicon germanium film or the like can be used. Although a thickness of 10 to 200 nm can be applied, the thickness may be further increased depending on the wavelength and energy density of the laser beam. In addition, it is preferable to provide a blocking layer 602 between the glass substrate 601 and the non-single-crystal semiconductor film 603 so as to prevent impurities such as alkali metals from diffusing from the glass substrate into the semiconductor film. As the blocking layer 602, a silicon nitride film, a silicon oxynitride film, or the like is used.
[0080]
Crystallization is performed by irradiation with the laser beam 600, so that a crystalline semiconductor film 604 can be formed. As shown in FIG. 14 (1 -A), the laser beam 600 is scanned in accordance with the position of the assumed semiconductor region 605 of the TFT.
The beam shape can be arbitrary, such as rectangular, linear, elliptical. Since the laser beam condensed by the optical system does not necessarily have a constant energy intensity at the center and the end, it is desirable that the semiconductor region 605 does not reach the end of the beam.
[0081]
The laser beam may be scanned not only in one direction but also in reciprocal scanning. In that case, it is possible to change the laser energy density for each scanning and to grow crystals in stages. It is also possible to serve as a hydrogen removal process that is often required when crystallizing an amorphous silicon film. First, scanning is performed at a low energy density, hydrogen is released, and then the energy density is increased to 2 Crystallization may be completed by the second scanning.
[0082]
After that, as shown in FIGS. 14 (2-A) and (2-B), the formed crystalline semiconductor film is etched to form a semiconductor region 605 divided into island shapes. In the case of a top gate TFT, a TFT can be formed by forming a gate insulating film 606, a gate electrode 607, and a one-conductivity type impurity region 608 over a semiconductor region 605. Thereafter, a wiring, an interlayer insulating film, or the like may be formed as necessary.
[0083]
In such a laser beam irradiation method, a crystal having a large grain size can be grown by irradiating a continuous wave laser beam. Of course, it is necessary to appropriately set detailed parameters such as the scanning speed and energy density of the laser beam, but this can be realized by setting the scanning speed to 10 to 80 cm / sec. The crystal growth rate after melting and solidification using a pulsed laser is said to be 1 m / sec, but the continuous crystal at the solid-liquid interface is scanned by scanning the laser beam at a slower rate and cooling it slowly. Growth is possible, and a large crystal grain size can be realized.
[0084]
[Example 3]
The method for manufacturing a TFT shown in Embodiment 2 can also be applied to a manufacturing process of a bottom-gate TFT in which a gate electrode is disposed between a substrate and a semiconductor film. As shown in FIG. 15A, a gate electrode 702 made of Mo or Cr is formed over a substrate 701, and a gate insulating film 703 in which a silicon nitride film and a silicon oxide film are stacked is formed. An amorphous silicon film 704 is formed thereover, and a crystalline silicon film 705 can be formed by irradiation with a laser beam 700.
[0085]
FIG. 15B shows another form of the bottom gate TFT, and shows a state in which the surface of the gate insulating film 706 is planarized. The planarization may be performed by chemical mechanical polishing. In the case of a bottom gate type TFT, a step is formed on the surface of the gate insulating film by forming the gate electrode first. In the crystal growth, such a step portion has a high probability of becoming a base point of crystal growth, that is, a crystal nucleus, and becomes a factor that inhibits uniform crystal growth. Therefore, it is considered desirable to flatten the surface of the gate insulating film in order to achieve uniform crystal growth.
[0086]
After the crystalline silicon film 705 is formed, a bottom gate TFT can be formed according to a known method such as formation of a semiconductor region and formation of a source and drain region.
[0087]
[Example 4]
An example of manufacturing a CMOS TFT using the laser processing apparatus of the present invention will be described with reference to FIGS.
[0088]
In FIG. 16A, a blocking layer 902 is formed to a thickness of 200 nm using silicon nitride oxide over a glass substrate 901 such as aluminosilicate glass or barium borosilicate glass. Thereafter, an amorphous silicon film 903 is formed to a thickness of 100 nm by plasma CVD. Crystallization is performed by irradiating a continuous wave laser beam 900, but the irradiation of the laser beam 900 is not necessarily performed on the entire surface of the amorphous silicon film 903.
[0089]
FIG. 16B shows the form of the active layer formation regions 905 and 906 divided into island shapes. As can be seen by comparing FIGS. 16A and 16B, the active layer formation region is crystallized. It is formed inside the area. Crystallization of the amorphous silicon film causes release of hydrogen contained therein and densification due to rearrangement of atoms, resulting in volume shrinkage. Therefore, lattice continuity is not ensured at the interface between the amorphous region and the crystal region, and distortion occurs. Therefore, forming the active layer formation region 905 of the TFT inside the crystallization region 904 also means removing this strain region. FIG. 17A shows a top view of this state.
[0090]
Here, the active layer refers to a semiconductor region including an impurity region whose valence electrons are controlled, such as a channel formation region and a source or drain region of a TFT.
[0091]
Further, a gate insulating film 907 is formed with a thickness of 80 nm. The gate insulating film 907 is formed by SiH using a plasma CVD method. _Four And N ₂ O to O ₂ As a reaction gas, a silicon oxynitride film is formed. Since this active layer has a high (100) plane orientation ratio, it is possible to reduce variations in the quality of the gate insulating film formed thereon, and hence to reduce variations in the threshold voltage of the TFT. it can.
[0092]
In FIG. 16C, gate electrodes 908 and 909 are formed over the gate insulating film 907. As a material for forming the gate electrode, a conductive material such as Al, Ta, Ti, W, or Mo or an alloy thereof is applied and formed to a thickness of 400 nm.
[0093]
FIG. 16D shows formation of an impurity region. By ion doping, a source or drain region 910 for an n-channel TFT, a lightly doped drain (LDD) region 911, and a source or drain region 912 for a p-channel TFT are formed. Form.
[0094]
By ion doping, the crystallinity of the region into which the impurity element is implanted is destroyed and becomes amorphous. Laser treatment is performed in order to recover the crystallinity and reduce the resistance by activating the impurity element. Laser treatment can be performed by the laser processing apparatus of the present invention. Alternatively, laser irradiation may be performed in a hydrogen atmosphere (reducing atmosphere) to perform hydrogenation.
[0095]
After that, as shown in FIG. 16E, an interlayer insulating film 914 is formed using a silicon nitride film or a silicon oxide film. Next, contact holes reaching the impurity regions of the respective semiconductor layers are formed, and wirings 915 and 916 are formed using Al, Ti, Ta, or the like. Further, a passivation film 917 is formed using a silicon nitride film. FIG. 17B shows a top view of this state.
[0096]
Thus, an n-channel TFT and a p-channel TFT can be formed.
Although each TFT is shown here as a single unit, a CMOS circuit, NMOS circuit, or PMOS circuit can be formed using these TFTs. Since the crystalline silicon film formed according to the present invention undergoes crystal growth parallel to the channel length direction, there is substantially no crystal grain boundary crossed by carriers, and high field effect mobility can be obtained. The TFT thus manufactured can be used as a TFT for manufacturing an active matrix type liquid crystal display device or a display device using a light emitting element, and as a TFT for forming a memory or a microprocessor on a glass substrate. it can.
[0097]
[Example 5]
A configuration example of a TFT substrate (substrate on which a TFT is formed) for realizing an active matrix drive type display device using TFTs manufactured in the same manner as in Embodiment 4 will be described with reference to FIG. In FIG. 18, a driver circuit portion 1806 having an n-channel TFT 1801, a p-channel TFT 1802, and an n-channel TFT 1803, and a pixel portion 1807 having a pixel TFT 1804 and a capacitor 1805 are formed over the same substrate.
[0098]
An n-channel TFT 1801 in the driver circuit portion 1806 includes a channel formation region 862, a second impurity region 863 partially overlapping with the gate electrode 810, and a first impurity region 864 functioning as a source region or a drain region. The p-channel TFT 1802 includes a channel formation region 865, a fourth impurity region 866 partially overlapping with the gate electrode 811, and a third impurity region 867 functioning as a source region or a drain region. The n-channel TFT 1803 includes a channel formation region 868, a second impurity region 869 that partially overlaps with the gate electrode 812, and a first impurity region 870 that functions as a source region or a drain region. A shift register circuit, a buffer circuit, a level shifter circuit, a latch circuit, or the like can be formed using such an n-channel TFT and a p-channel TFT.
[0099]
The active layer in which these channel formation region and impurity region are formed is formed in the same manner as in Example 2. Since the active layer is crystal-grown in the channel length direction and parallel to the substrate, the probability that carriers cross the grain boundary is greatly reduced. Thereby, high field effect mobility can be obtained and extremely excellent characteristics can be obtained.
[0100]
A pixel TFT 1804 in the pixel portion 1807 includes a channel formation region 871, a second impurity region 872 formed outside the gate electrode 813, and a first impurity region 873 functioning as a source region or a drain region. A third impurity region 876 to which boron is added is formed in the semiconductor film functioning as one electrode of the capacitor 1805. The capacitor 1805 is formed of an electrode 814 and a semiconductor film 806 using an insulating film (the same film as the gate insulating film) as a dielectric. Each of the second impurity regions functions as an LDD region and contains an impurity element for controlling valence electrons at a lower concentration than the first impurity region. Incidentally, reference numerals 853 to 860 denote various wirings, and reference numeral 861 corresponds to a pixel electrode.
[0101]
In these TFTs, the alignment ratio of the active layer for forming the channel formation region and the impurity region is high and flat, so that variations in the quality of the gate insulating film formed thereon can be reduced. Therefore, variation in the threshold voltage of the TFT can be reduced. As a result, the TFT can be driven with a low voltage, and there is an advantage that power consumption is reduced. In addition, since the surface is flattened, the electric field does not concentrate on the convex portion, so that deterioration due to the hot carrier effect generated particularly at the drain end can be suppressed. In addition, the concentration distribution of carriers flowing between the source and the drain is high near the interface with the gate insulating film, but since it is smoothed, the carriers can move smoothly without being scattered, and the field effect mobility. Can be increased.
[0102]
In order to manufacture a liquid crystal display device from such a TFT substrate, a counter substrate on which a common electrode is formed is provided with an interval of about 3 to 8 μm, and an alignment film and a liquid crystal layer are formed therebetween. Known techniques can be applied to these.
[0103]
FIG. 19 shows a circuit configuration of an active matrix substrate using the TFT substrate. A driver circuit portion for driving the TFT of the pixel portion 1901 is a data line driver circuit 1902 and a scanning line driver circuit 1903, and a shift register circuit, a buffer circuit, a level shifter circuit, a latch circuit, and the like are arranged as necessary. In this case, the data line driving circuit 1902 sends out a video signal, and the video signal from the controller 1904 and the timing signal for the scanning line driving circuit from the timing generator 1907 are input. A timing signal for the data line driving circuit from the timing generator 1907 is input to the scanning line driving circuit 1903, and a signal is output to the scanning line. The microprocessor 1906 performs control of the controller 1904, writing of data such as a video signal to the memory 1905, input / output from the external interface 1908, and operation management of the entire system.
[0104]
The TFTs for constituting these circuits can be formed with TFTs having a structure as shown in this embodiment. By making the active layer forming the channel formation region of the TFT a region that can be regarded as a single crystal, the characteristics of the TFT can be improved and various functional circuits can be formed on a substrate such as glass.
[0105]
[Example 6]
As another embodiment using a TFT substrate, an example of a display device using a light emitting element will be described with reference to the drawings. FIG. 20 is a cross-sectional view showing a pixel structure of a display device formed by disposing a TFT for each pixel. Note that the n-channel TFTs 2100 and 2102 and the p-channel TFT 2101 shown in FIG. 20 have the same configuration as that of the fourth embodiment, and detailed description thereof is omitted in this embodiment.
[0106]
FIG. 20A illustrates a structure in which an n-channel TFT 2100 and a p-channel TFT 2101 are formed in a pixel over a substrate 2001 with a blocking layer 2002 interposed therebetween. In this case, the n-channel TFT 2100 is a switching TFT, the p-channel TFT 2101 is a current control TFT, and its drain side is connected to one electrode of the light emitting element 2105. The p-channel TFT 2101 is intended to control the current flowing through the light emitting element. Needless to say, the number of TFTs provided in one pixel is not limited, and an appropriate circuit configuration can be obtained in accordance with the driving method of the display device.
[0107]
A light-emitting element 2105 illustrated in FIG. 20A includes an anode layer 2011, an organic compound layer 2012 containing a light-emitting body, and a cathode layer 2013, over which a passivation layer 2014 is formed. The organic compound layer includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. In addition, luminescence in an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning from a triplet excited state to a ground state, one of these, Or it contains both emissions.
[0108]
The material for forming the anode is a material having a high work function such as indium oxide, tin oxide or zinc oxide, and the cathode is an alkali metal or alkaline earth metal such as MgAg, AlMg, Ca, Mg, Li, AlLi or AlLiAg, Typically, a material having a low work function formed of a magnesium compound is used. Moreover, you may comprise a cathode by the combination of a 1-20 nm thin lithium fluoride layer and Al layer, and the combination of a thin cesium layer and Al layer. The anode is connected to the wiring 2010 on the drain side of the p-channel TFT 2101, and a partition layer 2003 is formed so as to cover the end of the anode 2011.
[0109]
A passivation film 2014 is formed over the light emitting element 2105. The passivation layer 2014 is formed using a material having a high barrier property against oxygen and water vapor, such as silicon nitride, silicon oxynitride, and diamond-like carbon (DLC). With such a configuration, light emitted from the light emitting element is emitted from the anode side.
[0110]
On the other hand, FIG. 20B illustrates a structure in which an n-channel TFT 2100 and an n-channel TFT 2102 are formed over a substrate 2001 with a blocking layer 2002 interposed therebetween. In this case, the n-channel TFT 2100 is a switching TFT, the n-channel TFT 2102 is a current control TFT, and its drain side is connected to one electrode of the light emitting element 2106.
[0111]
In the light-emitting element 2106, a film of a material having a high work function such as indium oxide, tin oxide, or zinc oxide is formed as the anode layer 2016 over the wiring 2015 connected to the drain side of the n-channel TFT 2102.
[0112]
The cathode formed on the organic compound layer 2018 has a first cathode layer 2019 formed of a material having a low work function of 1 to 2 nm and a cathode layer 2019 for reducing the resistance of the cathode. The second cathode layer 2017 is provided. The first cathode layer 2019 is made of cesium, an alloy of cesium and silver, lithium fluoride, alkali metal or alkaline earth metal such as MgAg, AlMg, Ca, Mg, Li, AlLi, and AlLiAg, typically a magnesium compound. It is formed. The second cathode layer 2017 is formed of a metal material such as Al or Ag having a thickness of 10 to 20 nm, or a transparent conductive film such as indium oxide, tin oxide or zinc oxide having a thickness of 10 to 100 nm. A passivation film 2020 is formed over the light emitting element 2106. With such a configuration, light emitted from the light emitting element is emitted from the cathode side.
[0113]
As another mode of the light-emitting element 2106 in FIG. 20B, as a cathode material on the wiring 2015 connected to the drain side of the n-channel TFT 2102, MgAg as a cathode material, MgAg in addition to lithium fluoride, A cathode layer 2016 made of an alkali metal or alkaline earth metal such as AlMg, Ca, Mg, Li, AlLi, AlLiAg, typically a magnesium compound, an organic compound layer 2018, a thin first anode layer 2019 having a thickness of about 1 to 2 nm, It can also be set as the 2nd anode layer 2017 formed with the transparent conductive film. The first anode layer is formed by vacuum deposition of a material having a high work function such as nickel, platinum, or lead.
[0114]
As described above, a display device using an active matrix light-emitting element can be manufactured. In these TFTs, the alignment ratio of the active layer for forming the channel formation region and the impurity region is high and flat, so that variations in the quality of the gate insulating film formed thereon can be reduced. Therefore, variation in the threshold voltage of the TFT can be reduced. As a result, it is possible to drive the TFT with a low voltage, and there is an advantage of reducing power consumption. This display device is suitable for the application because a high current driving capability is required for the TFT for controlling the current connected to the light emitting element. Although not shown here, the configuration in which the driver circuit portion is provided around the pixel portion may be the same as that in the fifth embodiment.
[0115]
[Example 7]
The present invention can be applied to various semiconductor devices. Examples of such semiconductor devices include portable information terminals (electronic notebooks, mobile computers, mobile phones, etc.), video cameras, digital cameras, personal computers, television receivers, mobile phones, projection display devices, and the like. Examples of these are shown in FIGS.
[0116]
FIG. 21A illustrates an example in which a television receiver is completed by applying the present invention, which includes a housing 3001, a support base 3002, a display portion 3003, and the like. A TFT substrate manufactured according to the present invention is applied to the display portion 3003.
[0117]
FIG. 21B shows an example of a video camera completed by applying the present invention, which includes a main body 3011, a display portion 3012, an audio input portion 3013, an operation switch 3014, a battery 3015, an image receiving portion 3016, and the like. . A TFT substrate manufactured according to the present invention is applied to the display portion 3012.
[0118]
FIG. 21C illustrates an example in which a laptop personal computer is completed by applying the present invention, which includes a main body 3021, a housing 3022, a display portion 3023, a keyboard 3024, and the like. A TFT substrate manufactured according to the present invention is applied to the display portion 3023.
[0119]
FIG. 21D is an example in which a PDA (Personal Digital Assistant) is completed by applying the present invention, and includes a main body 3031, a stylus 3032, a display portion 3033, operation buttons 3034, an external interface 3035, and the like. A TFT substrate manufactured according to the present invention can be applied to the display portion 3033.
[0120]
FIG. 21E is an example in which the present invention is applied to complete a sound reproducing device. Specifically, the audio reproducing device is a vehicle-mounted audio device, which includes a main body 3041, a display portion 3042, operation switches 3043, 3044, and the like. Has been. A TFT substrate manufactured according to the present invention can be applied to the display portion 3042.
[0121]
FIG. 21F illustrates an example in which the present invention is applied to complete a digital camera. A main body 3051, a display portion (A) 3052, an eyepiece portion 3053, an operation switch 3054, a display portion (B) 3055, a battery 3056. Etc. The TFT substrate manufactured according to the present invention can also be applied to the display portion (A) 3052 and the display portion (B) 3055.
[0122]
FIG. 21G illustrates an example of a cellular phone completed by applying the present invention, which includes a main body 3061, an audio output unit 3062, an audio input unit 3063, a display unit 3064, operation switches 3065, an antenna 3066, and the like. Yes. A TFT substrate manufactured according to the present invention can be applied to the display portion 3064.
[0123]
FIG. 22A illustrates a front type projector, which includes a projection device 2601, a screen 2602, and the like. FIG. 22B shows a rear projector, which includes a main body 2701, a projection device 2702, a mirror 2703, a screen 2704, and the like.
[0124]
Note that FIG. 22C is a diagram illustrating an example of the structure of the projection devices 2601 and 2702 in FIGS. 22A and 22B. The projection devices 2601 and 2702 include a light source optical system 2801, mirrors 2802, 2804 to 2806, a dichroic mirror 2803, a prism 2807, a liquid crystal display device 2808, a phase difference plate 2809, and a projection optical system 2810. Projection optical system 2810 includes an optical system including a projection lens. Although the present embodiment shows a three-plate type example, it is not particularly limited, and for example, a single-plate type may be used. In addition, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, or an IR film in the optical path indicated by an arrow in FIG. Good.
[0125]
FIG. 22D is a diagram illustrating an example of the structure of the light source optical system 2801 in FIG. In this embodiment, the light source optical system 2801 includes a reflector 2811, a light source 2812, lens arrays 2813 and 2814, a polarization conversion element 2815, and a condenser lens 2816. Note that the light source optical system illustrated in FIG. 22D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, or an IR film in the light source optical system.
[0126]
It should be noted that the electronic device exemplified here is only an example and is not limited to these applications.
[0127]
【The invention's effect】
As described above, according to the present invention, a crystal semiconductor film having a large grain size can be obtained by irradiating a laser beam over the entire surface of a large area substrate in accordance with the position of a semiconductor region where a TFT is formed, and crystallizing it. In addition, TFT characteristics can be improved.
[0128]
In particular, with the configuration of the laser processing apparatus of the present invention, a laser beam having an energy density sufficient to melt the semiconductor can be irradiated without causing interference in the irradiation unit. Further, the amorphous semiconductor film can be crystallized over the entire surface of the large area substrate by scanning the laser beam with the deflecting means.
Alternatively, the specified region on the large area substrate can be selectively crystallized by the deflecting means. Furthermore, the influence of interference can be removed by superimposing a plurality of laser beams on the same irradiation part by the deflecting means.
[0129]
Therefore, according to the present invention, it is possible to form a crystalline semiconductor film with high throughput by irradiating a laser beam over the entire surface of a large area substrate in accordance with the position of the semiconductor region where the TFT is formed and crystallizing. The characteristics of the TFT can be improved.
[Brief description of the drawings]
FIG. 1 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 2 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 3 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 4 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 5 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 6 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 7 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 8 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 9 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 10 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 11 is a diagram for explaining the relationship between the structure of a TFT substrate, the arrangement of semiconductor regions constituting the TFT, and the scanning direction of the laser beam.
FIG. 12 is a diagram for explaining the relationship between the configuration of a TFT substrate, the arrangement of semiconductor regions constituting the TFT, and the scanning direction of the laser beam.
FIG. 13 is a diagram for explaining the relationship between the structure of a TFT substrate, the arrangement of semiconductor regions constituting the TFT, and the scanning direction of the laser beam.
FIGS. 14A and 14B illustrate a scanning direction of a laser beam in a semiconductor film and a manufacturing process of a TFT. FIGS.
FIG. 15 is a cross-sectional view illustrating a manufacturing process of a bottom-gate TFT.
FIG. 16 is a cross-sectional view illustrating a manufacturing process of a TFT.
FIG. 17 is a top view illustrating a manufacturing process of a TFT.
FIG. 18 is a cross-sectional view showing a configuration of a TFT substrate.
FIG. 19 is a block diagram showing an example of a circuit configuration of a TFT substrate.
FIG. 20 is a cross-sectional view illustrating a structure of a pixel of a semiconductor device provided with a light-emitting element.
FIG. 21 illustrates an example of a semiconductor device.
FIG 22 illustrates an example of a semiconductor device.
FIG. 23 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
FIG. 24 is a layout view showing one embodiment of a laser processing apparatus of the present invention.
25A and 25B illustrate a laser beam scanning direction in a semiconductor film and a manufacturing process of a TFT.

Claims (18)

A plurality of optical systems including a laser oscillation device and a first deflecting unit that deflects a laser beam output from the laser oscillation device in the main scanning direction;
By receiving a plurality of laser beams deflected in the main scanning direction, and a second deflecting means for scanning in the sub-scanning direction,
The second deflecting unit has a function of scanning the plurality of laser beams in the sub-scanning direction according to a rotation angle about an axis in one axial direction and irradiating the workpiece on the mounting table with the laser beams. A laser processing apparatus comprising: A plurality of optical systems each including a laser oscillation device and a first movable mirror that deflects a laser beam output from the laser oscillation device in the main scanning direction;
By receiving a plurality of laser beams deflected in the main scanning direction, and a second movable mirror elongated scanning in the sub-scanning direction,
The second movable mirror has a function of scanning the plurality of laser beams in the sub-scanning direction at a rotation angle about the longitudinal axis and irradiating the workpiece on the mounting table with the laser beams. The laser processing apparatus characterized by having. A plurality of sets of first optical systems each including a first laser oscillation device and first deflection means for deflecting a laser beam output from the first laser oscillation device in a first main scanning direction;
Second deflection means for receiving a plurality of laser beams deflected in the first main scanning direction and scanning in the first sub-scanning direction;
A plurality of sets of second optical systems each including a second laser oscillation device and third deflection means for deflecting the laser beam output from the second laser oscillation device in the second main scanning direction;
Receiving a plurality of laser beams deflected in the second main scanning direction and scanning in the second sub-scanning direction;
The second and fourth deflecting units scan a plurality of laser beams in the first or second sub-scanning direction at a rotation angle about a uniaxial direction, and on the workpiece mounting table on the mounting table. A laser processing apparatus having a function of irradiating an object to be processed with the laser beam. A plurality of first optical systems each including a first laser oscillation device and a first movable mirror that deflects a laser beam output from the first laser oscillation device in a first main scanning direction;
A long second deflection mirror that receives a plurality of laser beams deflected in the first main scanning direction and scans in the first sub-scanning direction;
A plurality of sets of second optical systems each including a second laser oscillation device and a third deflection mirror that deflects the laser beam output from the second laser oscillation device in the second main scanning direction;
A long fourth deflecting mirror that receives a plurality of laser beams deflected in the second main scanning direction and scans in the second sub-scanning direction;
The second and fourth deflecting mirrors scan a plurality of laser beams in the first or second sub-scanning direction at a rotation angle about a uniaxial direction, and on the processing object mounting table on the mounting table. A laser processing apparatus having a function of irradiating an object to be processed with the laser beam. In claim 1 or claim 2,
A laser processing apparatus, wherein the optical system includes an fθ lens. In claim 1 or claim 2,
The laser processing apparatus is a continuous wave solid state laser oscillation apparatus. In claim 1 or claim 2,
The laser processing apparatus, wherein the laser oscillation apparatus is a laser oscillation apparatus that continuously outputs a laser beam having a wavelength of 700 nm or less. In claim 1 or claim 2,
The laser processing apparatus, wherein the laser beam output from the laser oscillation apparatus is obtained by superimposing laser beams output from a plurality of laser oscillation apparatuses on the same optical axis. A plurality of first deflecting means for deflecting the plurality of laser beams in the main scanning direction;
A second deflecting unit that receives the laser beam deflected in the main scanning direction and scans the laser beam in the sub-scanning direction at a rotation angle about an axis in a uniaxial direction; Scan in the direction
A method for manufacturing a semiconductor device , wherein the semiconductor film formed over an insulating surface is irradiated with the laser beam to crystallize the semiconductor film having an amorphous structure. A plurality of first deflecting means for deflecting the plurality of laser beams in the main scanning direction;
A second deflecting unit that receives the laser beam deflected in the main scanning direction and scans the laser beam in the sub-scanning direction by a rotation angle about an axis in a uniaxial direction; Scanning in the sub-scanning direction while irradiating a semiconductor film having an amorphous structure formed thereon, and crystallizing the semiconductor film,
A method for manufacturing a semiconductor device, wherein a semiconductor region is formed so that the sub-scanning direction and a channel length direction of a thin film transistor coincide with each other. A plurality of first deflecting means for deflecting each of the plurality of first laser beams in the first main scanning direction;
Second deflecting means for receiving the first laser beam deflected in the first main scanning direction and scanning the first laser beam in the first sub-scanning direction by a rotation angle about a uniaxial axis;
A plurality of third deflecting means for deflecting each of the plurality of second laser beams in the second main scanning direction;
A fourth deflecting unit that receives the second laser beam deflected in the second main scanning direction and scans the second laser beam in the second sub-scanning direction at a rotation angle about an axis in one axis direction;
The first laser beam is scanned in the first sub-scanning direction, the second laser beam is scanned in the second sub-scanning direction, and a semiconductor film having an amorphous structure formed on an insulating surface is formed on the semiconductor film . A method for manufacturing a semiconductor device, characterized by irradiating a laser beam to crystallize the semiconductor film . A plurality of first deflecting means for deflecting each of the plurality of first laser beams in the first main scanning direction;
Second deflecting means for receiving the first laser beam deflected in the first main scanning direction and scanning the first laser beam in the first sub-scanning direction by a rotation angle about a uniaxial axis;
A plurality of third deflecting means for deflecting each of the plurality of second laser beams in the second main scanning direction;
A fourth deflecting unit that receives the second laser beam deflected in the second main scanning direction and scans the second laser beam in the second sub-scanning direction at a rotation angle about an axis in one axis direction;
The first laser beam is scanned in the first sub-scanning direction while irradiating the semiconductor film having an amorphous structure formed on the insulating surface with the first or second laser beam, and the second laser beam is scanned. Scanning the beam in the second sub-scanning direction to crystallize the semiconductor film;
A manufacturing method of a semiconductor device, wherein a semiconductor region is formed so that the first sub-scanning direction and the second sub-scanning direction and a channel length direction of a thin film transistor coincide with each other. A plurality of first deflecting means for deflecting the plurality of laser beams in the main scanning direction;
By receiving the laser beam deflected before Symbol main scanning direction, by a second deflecting means for scanning in a sub-scanning direction respectively by the rotational angle around the axis of the uniaxial direction,
Scanning the plurality of laser beams in the sub-scanning direction;
A method for manufacturing a semiconductor device , comprising: irradiating a region into which a non-single-crystal semiconductor ion is implanted with the laser beam to recover crystallinity of the region . A plurality of first deflecting means for deflecting a plurality of laser beams in the main scanning direction, respectively,
By receiving the laser beam deflected before Symbol main scanning direction, by a second deflecting means for scanning in a sub-scanning direction respectively by the rotational angle around the axis of the uniaxial direction,
Scanning in the sub-scanning direction while irradiating the non-single crystal semiconductor film formed on the insulating surface with the plurality of laser beams to restore the crystallinity of the region into which the ions of the non-single crystal semiconductor film are implanted. ,
A method for manufacturing a semiconductor device, wherein a semiconductor region is formed so that the sub-scanning direction and a channel length direction of a thin film transistor coincide with each other. A plurality of first deflecting means for deflecting each of the plurality of first laser beams in the first main scanning direction;
Second deflecting means for receiving the first laser beam deflected in the first main scanning direction and scanning the first laser beam in the first sub-scanning direction by a rotation angle about a uniaxial axis;
A plurality of third deflecting means for deflecting each of the plurality of second laser beams in the second main scanning direction;
A fourth deflecting unit that receives the second laser beam deflected in the second main scanning direction and scans the second laser beam in the second sub-scanning direction at a rotation angle about an axis in one axis direction;
The first laser beam is scanned in the first sub-scanning direction, the second laser beam is scanned in the second sub-scanning direction, and the laser beam is irradiated to the region where the non-single crystal semiconductor ions are implanted. And recovering the crystallinity of the region . A plurality of first deflecting means for deflecting each of the plurality of first laser beams in the first main scanning direction;
Second deflecting means for receiving the first laser beam deflected in the first main scanning direction and scanning the first laser beam in the first sub-scanning direction by a rotation angle about a uniaxial axis;
A plurality of third deflecting means for deflecting each of the plurality of second laser beams in the second main scanning direction;
A fourth deflecting unit that receives the second laser beam deflected in the second main scanning direction and scans the second laser beam in the second sub-scanning direction at a rotation angle about an axis in one axis direction;
While irradiating the non-single crystal semiconductor film formed on the insulating surface with the first or second laser beam, the first laser beam is scanned in the first sub-scanning direction, and the second laser beam is scanned with the second laser beam. Scanning in the sub-scanning direction to recover the crystallinity of the region into which ions of the non-single crystal semiconductor film are implanted,
A manufacturing method of a semiconductor device, wherein a semiconductor region is formed so that the first sub-scanning direction and the second sub-scanning direction and a channel length direction of a thin film transistor coincide with each other. In claim 9 or 10,
A method of manufacturing a semiconductor device, wherein the laser beam is a laser beam output from a continuous wave solid-state laser oscillation device. In claim 9 or 10,
A method for manufacturing a semiconductor device, wherein the laser beam is a continuous wave laser beam having a wavelength of 400 nm or more.

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